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A247087
a(n) = pi(phi(p(P(n)))) = A000720(A000010(A000041(A000040(n)))).
1
0, 1, 3, 4, 9, 25, 41, 39, 168, 462, 442, 1939, 2571, 3998, 5123, 17040, 24853, 38887, 195022, 183430, 404386, 381060, 1162366, 2105509, 1799881, 5966593, 5380661, 14184985, 10473967, 22631261, 135452589, 109540327, 244730051, 487610708, 604467085, 671043205, 3350187738
OFFSET
1,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..90 (calculated using Kim Walisch's primecount)
FORMULA
MAPLE
with(numtheory): with(combinat): p:=numbpart: P:=ithprime:
a:= n-> pi(phi(p(P(n)))):
seq(a(n), n=1..20);
MATHEMATICA
a[n_] := PrimePi @ EulerPhi @ PartitionsP @ Prime @ n;
Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Mar 25 2017 *)
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Mar 14 2015
EXTENSIONS
a(31)-a(37) from Amiram Eldar, Sep 03 2024
STATUS
approved